This invention relates to esters, amides and N-substituted amides of 2-[N-(morpholinoalkyl)aminosulfonyl]-6-nitrobenzoic acids, used as sensitizers of hypoxic tumor cells to therapeutic radiation. It also relates to the process of preparing such compounds starting with a 2-chlorosulfonyl-6-nitrobenzoate ester prepared as described in U.S. Ser. No. 716,886 filed Mar. 27, 1985 and aminating said 2-chlorosulfonylbenzoate ester to produce the corresponding sulfamyl or N-substituted sulfamylnitrobenzoic esters.
At the present time, certain other unrelated compounds are in experimental clinical use as radiation sensitizers. However, these compounds--for example, metronidazole and misonidazole--suffer from the drawback that they also cause neurotoxicity which limits their usefulness. The compounds of the present invention are effective radiation sensitizers, and are believed to have a more favorable therapeutic ratio.